The analytical chemistry is a branch of chemistry that is interested in the determination and quantitation of compounds. It implements state-of-the-art techniques requiring expensive instrumentation. The analysis can be qualitative (characterization) or quantitative (dosage). Read on to get more info now.
Among the methods of anesthetic chemistry are:
The chromatography: an indispensable tool for the separation and identification of compounds from a mixture
The infrared, the nuclear magnetic resonance, and mass spectrometry: 3 complementary techniques to determine the structure of molecules.
Note: The chemistry is said to be “qualitative” or “quantitative” depending on whether one looks for the nature of the component elements or the proportion of each of them.
Until the beginning of the twentieth century, analytical chemistry consisted of reacting the unknown product with known products to determine its nature. The introduction of quantitative methods, using the concepts of physical chemistry, marked a renewal of analytical chemistry. Nowadays, we use physics-based methods to determine and quantify a range of elements in a single operation.
Analytical methods
Before analyzing a compound, a sample is taken, and the various constituents of the mixture are separated. If the mixture consists of several phases, we first separate these phases. For example, the solid phase can be separated from the liquid phase by filtration or sieving. The separation of a homogeneous mixture uses the differences in physical properties between the constituents. For example, the salt is easily extracted from a salt-sand mixture by means of water, since the salt is soluble in water and sand is not. On the other hand, iron filings and sand are both insoluble in water and cannot be separated by differences in solubility in this liquid. However, only iron filings are magnetic, so it can be recovered by magnetic sorting. Liquid components can be separated by successive or fractional distillations. In some cases, successive crystallizations make it possible to separate the solid constituents.
The analysis can, therefore, be classified:
According to the type: qualitative or quantitative analysis:
Qualitative analysis can be by classical or instrumental methods.
The sample is subjected to the analysis either to know the identity of its constituents or to determine the contents of its constituents. If we do not know what kind of material we are dealing with, it may be necessary to do a qualitative analysis before doing quantitative analysis.
According to the way of executing it: classical analysis, or instrumental analysis:
The techniques of classical analysis use quantitative reactions. The instruments used are simple (graduated test tubes, graduated pipettes), analytical balances, pH meters. They are usually destructive. When they use aqueous solutions, it is called “wet.”
The techniques of instrumental analysis use apparatus that allows determinations based on physical properties, performed either on the sample as such (it is non-destructive), on prepared solids, or on sample solutions.
Depending on the target product: mineral or organic analysis:
The mineral analysis applies to the non-organic product but also to the minerals contained in organic products.
Depending on the number of samples used: macro or microanalysis:
Destructive or non-destructive analysis: In general, classical analysis is destructive, and instrumental analysis is not always.
The quantitative analysis makes it possible to determine the concentration of the various elements, or compounds sought. In analytical chemistry, it is the measurement of the quantities of elements, or compounds, present in a volume. In this, it is complementary to the qualitative analysis in which one only seeks to determine whether one or another element or compound, is present or not.
Classical qualitative analysis is a non-instrumental method of chemical analysis that looks for the elemental composition of compounds. It is the search for presence, or not, of certain elements or compounds.